The innate immune system is the mosquito's main line of defense against the malaria parasite Plasmodium at multiple stages of the parasite's life cycle. These immune responses are largely regulated by the TOLL and IMD pathways, which control the nuclear translocation of the NF-kappaB-like transcription factors, Rel1 and Rel2, respectively. While both pathways are implicated in anti-Plasmodium defense, we have shown that the IMD pathway is a conserved key player in regulating resistance of several Anopheles species to multiple malaria parasite species including the human pathogen P. falciparum. We have shown that the Rel2 transcription factor - mediate anti- Plasmodium action through multiple effectors and that the fitness cost of a transient induction of the Rel2 activation is minimal. As such, the IMD pathway is particularly interesting for the development of genetically modified Plasmodium resistant mosquitoes. This proposal will focus on a better understanding of the Rel2 mediated resistance to Plasmodium and thereby assess the feasibility to use this system for the development of malaria control strategies. The overall aim of this project is to develop transgenic mosquitoes that can activate Rel2 mediated anti-Plasmodium defense at an appropriate stage of infection. These mosquitoes will be used to study the regulation of this defense system and dissect the genes and mechanisms that is responsible for Plasmodium killing.